Capacity Estimation for Roundabouts with High Truck Volume Using Gap Acceptance Theory

141 Pages·2015·6.42 MB·English

by  Jason Dahl

University of Windsor
Scholarship at UWindsor
Electronic Theses and Dissertations
2011
Capacity Estimation for Roundabouts with High
Truck Volume Using Gap Acceptance Theory
Jason Dahl
University of Windsor
Follow this and additional works at:http://scholar.uwindsor.ca/etd
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Dahl, Jason, "Capacity Estimation for Roundabouts with High Truck Volume Using Gap Acceptance Theory" (2011).Electronic Theses
and Dissertations.Paper 76.
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Capacity Estimation for Roundabouts with High
Truck Volume Using Gap Acceptance Theory

By

Jason Dahl

A Thesis
Submitted to the Faculty of Graduate Studies
through the Department of Civil and Environmental Engineering
in Partial Fulfillment of the Requirements for the Degree of Master of Applied Science
at the University of Windsor

Windsor, Ontario, Canada

2011

© 2011 Jason Dahl
Capacity Estimation for Roundabouts with High
Truck Volume Using Gap Acceptance Theory

By

Jason Dahl

APPROVED BY:

______________________________________________
Dr. H. Maoh, Department Reader
Department of Civil and Environmental Engineering

______________________________________________
Dr. W. Anderson, Outside Program Reader
Department of Political Science

______________________________________________
J. Tofflemire, Special Advisor
Department of Civil and Environmental Engineering

______________________________________________
Dr. C. Lee, Advisor
Department of Civil and Environmental Engineering

______________________________________________
Dr. B. Budkowska, Chair of Defense
Department of Civil and Environmental Engineering

September 12th, 2011
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DECLARATION OF PREVIOUS PUBLICATION
This thesis includes material from two original papers that have been previously submitted for
publication in a peer reviewed journal, as follows:
Dahl, J. and C. Lee (2011). Empirical Estimation of Capacity for Roundabouts Using Adjusted
Gap-Acceptance Parameters for Trucks. Submitted for presentation at the 91st Transportation
Research Board Annual meeting, and for publication in the Transportation Research Record.
Washington, D.C., 20 pages.

I certify that I have obtained a written permission from the copyright owner(s) to include the
above published material(s) in my thesis. I certify that the above material describes work
completed during my registration as a graduate student at the University of Windsor.
I declare that, to the best of my knowledge, my thesis does not infringe upon anyone’s copyright
nor violate any proprietary rights and that any ideas, techniques, quotations, or any other material
from the work of other people included in my thesis, published or otherwise, are fully
acknowledged in accordance with the standard referencing practices. Furthermore, to the extent
that I have included copyrighted material that surpasses the bounds of fair dealing within the
meaning of the Canada Copyright Act, I certify that I have obtained written permission from the
copyright owner(s) to include such material(s) in my thesis.
I declare that this is a true copy of my thesis, including any final revisions, as approved by my
thesis committee and the Graduate Studies office, and that this thesis has not been submitted for
a higher degree to any other University or Institution.
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ABSTRACT
This study examines the effect of heavy vehicles (trucks) on entry capacity of roundabouts. The
movements of vehicles were observed at 11 roundabouts in Vermont, Ontario and Wisconsin.
Gap-acceptance parameters were estimated for cars and trucks separately; consistent with
previous studies, it was found that critical headway and follow-up time were longer for trucks
than cars. Follow-up times for truck-involved vehicle-following cases were found to be
associated with central island diameter and entry angle. Gap-acceptance parameters for all
entering vehicles were adjusted to a volume-weighted average of the gap-acceptance parameters
for cars and trucks. Entry capacity was estimated using existing capacity models with the
adjusted gap-acceptance parameters, and compared with the observed capacity at three
roundabouts. The capacity models with adjusted gap-acceptance parameters estimated capacity
more accurately than the models with unadjusted parameters. Microscopic traffic simulation
model was also effective in representing truck characteristics and their impact on roundabout
operation.

Keywords: Roundabout, Capacity, Truck, Heavy vehicle, Gap acceptance

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ACKNOWLEDGEMENTS
I would personally like to thank my supervisor, Dr. Chris Lee, for his continued support,
guidance, assistance, and overall persistence throughout the course of this project. His
encouragement has allowed me to learn and accomplish much more than I had expected, travel to
various parts of the continent, and recapture my excitement in this field of engineering. Thanks
to my evaluation committee of Dr. Hanna Maoh, Dr. William P. Anderson, Mr. John D.
Tofflemire, and Dr. Barabara Budkowska. Additional thanks to Dr. Sreekanta Das and Dr.
Shaohong Cheng for guidance while considering grad school. Thanks to Ms. Adinda Van Espen
for helping me collect some field data from video footage.

Thanks also goes to Ms. Andrea Bill at the University of Wisconsin-Madison, Mr. Patrick
Fleming at Wisconsin Department of Transportation, Mr. Egerton Heath at Region of Waterloo
and Mr. Lee A. Rodegerdts at Kittelson & Associates, Inc. for providing the video records and
geometric drawings used in the study. I would also thank Dr. Ning Wu and Dr. Rod Troutbeck for
providing the information on the critical headway. This research was supported by the Natural
Sciences and Engineering Research Council of Canada (NSERC).

I would like to thank all of my friends and colleagues at the University, specifically Corey and
Kevin, for their support and kind words; it’s good to not be suffering alone (just kidding). I’d
also like to thank my friends outside of graduate school, for keeping me focused and positive.
Thanks to Adam, Amy, Heather, Jeff, Jordan, Mark, and Sarah; and thanks to all of the
roommates and band mates I’ve had the privilege to meet these last few years. Extra thanks to
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Charles, Pawel and Sonia, for lending me their homes, couches and pantries while I attended
conferences outside of Windsor during this time.

Finally, thanks to my family, for always encouraging me to continue my education. Special
thanks to Aunt Jane and Uncle Dave, and to my grandparents Nick and Anna Bauer, for their
boundless love, support and belief in me. Thanks for helping me become the person I am today.
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TABLE OF CONTENTS
DECLARATION OF PREVIOUS PUBLICATION ..................................................................... iii
ABSTRACT ................................................................................................................................... iv
ACKNOWLEDGEMENTS ............................................................................................................ v
LIST OF TABLES .......................................................................................................................... x
LIST OF FIGURES ...................................................................................................................... xii
NOMENCLATURE ..................................................................................................................... xv
1 INTRODUCTION .................................................................................................................... 1
1.1 Overview ....................................................................................................................... 1
1.2 Objectives of Thesis ...................................................................................................... 5
1.3 Organization of Thesis .................................................................................................. 5
2 LITERATURE REVIEW ......................................................................................................... 6
2.1 Gap Acceptance Capacity Models ................................................................................ 6
2.1.1 Headway Distribution ................................................................................. 6
2.1.2 Capacity Models ......................................................................................... 8
2.1.3 Critical Headway ...................................................................................... 10
2.1.4 Effects of Exiting Vehicles on Capacity ................................................... 12
2.2 Empirical Capacity Models......................................................................................... 14
2.3 Microscopic Traffic Simulation Models ..................................................................... 17
2.4 Effect of Trucks on Capacity ...................................................................................... 19
3 PROCEDURE ......................................................................................................................... 21
3.1 Capacity Model using Adjusted Gap-Acceptance Parameters ................................... 21
3.1.1 Adjusting Critical Headway ...................................................................... 21
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3.1.2 Adjusting Follow-up Time ........................................................................ 22
3.1.3 Adjusting Capacity.................................................................................... 23
3.2 Capacity Estimation using Computerized Models ...................................................... 23
4 DATA ..................................................................................................................................... 25
4.1 Studied Roundabouts .................................................................................................. 25
4.2 Data Collection ........................................................................................................... 30
4.2.1 Gap Acceptance/Rejection Data ............................................................... 30
4.2.2 Follow-up Time Data ................................................................................ 32
4.2.3 Free-flow Speed Data ............................................................................... 32
4.2.4 Entry Capacity and Turning Movement Data ........................................... 34
4.2.5 Calibration of Computerized Models........................................................ 36
5 RESULTS AND DISCUSSION ............................................................................................. 41
5.1 Headway Distribution ................................................................................................. 41
5.2 Free-flow Speed .......................................................................................................... 43
5.3 Critical Headway ........................................................................................................ 44
5.4 Follow-up Time .......................................................................................................... 47
5.5 Geometric Factors ....................................................................................................... 48
5.6 Capacity Estimation for Existing Conditions ............................................................. 52
5.7 Capacity Estimation for Hypothetical Cases of Truck Percentage ............................. 59
6 CONCLUSIONS AND RECOMMENDATIONS ................................................................. 63
REFERENCES ............................................................................................................................. 67
APPENDICES .............................................................................................................................. 72
Appendix A – Geometric Drawings .................................................................................. 72
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Appendix B – Video Screenshots ..................................................................................... 83
Appendix C – Gap Acceptance Data (32&57 Roundabout) ............................................. 89
Appendix D – Roundabout Headway Distributions ......................................................... 98
Appendix E – Critical Headway Graphical Method ....................................................... 104
Appendix F –Probability Equilibrium Method (32&57 Roundabout) ............................ 114
Appendix G – Linear Regression Statistics .................................................................... 120
VITA AUCTORIS ...................................................................................................................... 124

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